A Lagrange-D'Alembert formulation of the equations of motion of a helicopter carrying an externally suspended load

The exact nonlinear equations of motion are derived for a helicopter with an extenal load suspended by fore and aft, rigid-link cables. Lagrange's form of D'Alembert's principle is used. Ten degrees of freedom are necessary to represent the motion of this system in an inertial reference frame: six for the helicopter relative to inertial space and four for the load relative to the helicopter

Rotor redesign for a highly loaded 1800 ft/sec tip speed fan. 1: Aerodynamic and mechanical design report

A quasi three dimensional design system and multiple-circular-arc airfoil sections were used to design a fan rotor. An axisymmetric intrablade flow field calculation modeled the shroud of an isolated splitter and radial distribution. The structural analysis indicates that the design is satisfactory for evaluation of aerodynamic performance of the fan stage in a test facility

Citizens without nations

To broach the question of whether citizenship could exist without (or beyond) community, this paper discusses genealogies of citizenship as membership that binds an individual to the community of birth (of the self or a parent). It is birthright as fraternity that blurs the boundary between citizenship and nationality. After briefly discussing recent critical studies on birthright citizenship (whether it is civic or ethnic or blood or soil) by Ayelet Shachar and Jacqueline Stevens, the paper discusses three critical genealogies of the relationship between birthright and citizenship by Max Weber, Hannah Arendt, and Michel Foucault. Although each provides a critical perspective into the question, Weber reduces citizenship to fraternity with nation and Arendt reduces citizenship to fraternity with the state. It is Foucault who illustrates racialization of fraternity as the connection between citizenship and nationality. Yet, since Foucault limits his genealogical investigations to the 18th and 19th centuries, a genealogy of fraternity of what he calls an immense biblical and Greek tradition remains for Derrida to articulate as a question of citizenship

Classical versus Quantum Time Evolution of Densities at Limited Phase-Space Resolution

We study the interrelations between the classical (Frobenius-Perron) and the quantum (Husimi) propagator for phase-space (quasi-)probability densities in a Hamiltonian system displaying a mix of regular and chaotic behavior. We focus on common resonances of these operators which we determine by blurring phase-space resolution. We demonstrate that classical and quantum time evolution look alike if observed with a resolution much coarser than a Planck cell and explain how this similarity arises for the propagators as well as their spectra. The indistinguishability of blurred quantum and classical evolution implies that classical resonances can conveniently be determined from quantum mechanics and in turn become effective for decay rates of quantum correlations.Comment: 10 pages, 3 figure

Results of NASA/FAA ground and flight simulation experiments concerning helicopter IFR airworthiness criteria

A sequence of ground and flight simulation experiments was conducted to investigate helicopter instrument-flight-rules airworthiness criteria. The first six of these experiments and major results are summarized. Five of the experiments were conducted on large-amplitude motion base simulators. The NASA-Army V/STOLAND UH-1H variable-stability helicopter was used in the flight experiment. Artificial stability and control augmentation, longitudinal and lateral control, and in pitch and roll attitude augmentation were investigated

Upper limits on stray force noise for LISA

We have developed a torsion pendulum facility for LISA gravitational reference sensor ground testing that allows us to put significant upper limits on residual stray forces exerted by LISA-like position sensors on a representative test mass and to characterize specific sources of disturbances for LISA. We present here the details of the facility, the experimental procedures used to maximize its sensitivity, and the techniques used to characterize the pendulum itself that allowed us to reach a torque sensitivity below 20 fNm /sqrt{Hz} from 0.3 to 10 mHz. We also discuss the implications of the obtained results for LISA.Comment: To be published in Classical and Quantum Gravity, special issue on Amaldi5 2003 conference proceedings (10 pages, 6 figures

Component-specific modeling

Accomplishments are described for a 3 year program to develop methodology for component-specific modeling of aircraft hot section components (turbine blades, turbine vanes, and burner liners). These accomplishments include: (1) engine thermodynamic and mission models, (2) geometry model generators, (3) remeshing, (4) specialty three-dimensional inelastic structural analysis, (5) computationally efficient solvers, (6) adaptive solution strategies, (7) engine performance parameters/component response variables decomposition and synthesis, (8) integrated software architecture and development, and (9) validation cases for software developed

Enhanced secondary organic aerosol formation due to water uptake by fine particles

This study characterizes the partitioning behavior of a significant fraction of the ambient organic aerosol through simultaneous measurements of gas and particle watersoluble organic carbon (WSOC). During the summer in Atlanta, WSOC gas/particle partitioning showed a strong RH dependence that was attributed to particulate liquid water. At elevated RH levels (\u3e70%) a significant increase in WSOC partitioning to the particle phase was observed and followed the predicted water uptake by fine particles. The enhancement in particle-phase partitioning translated to increased median particle WSOC concentrations ranging from 0.3 –0.9 mgCm3 . The results provide a detailed overview of the WSOC partitioning behavior in the summertime in an urban region dominated by biogenic emissions, and indicate that secondary organic aerosol formation involving partitioning to liquid water may be a significant aerosol formation route that is generally not considered. Citation: Hennigan, C. J., M. H. Bergin, J. E. Dibb, and R. J. Weber (2008), Enhanced secondary organic aerosol formation due to water uptake by fine particles, Geophys. Res. Lett., 35, L18801, doi:10.1029/2008GL035046

Neutron Charge Radius: Relativistic Effects and the Foldy Term

The neutron charge radius is studied within a light-front model with different spin coupling schemes and wave functions. The cancellation of the contributions from the Foldy term and Dirac form factor to the neutron charge form factor is verified for large nucleon sizes and it is independent of the detailed form of quark spin coupling and wave function. For the physical nucleon our results for the contribution of the Dirac form factor to the neutron radius are insensitive to the form of the wave function while they strongly depend on the quark spin coupling scheme.Comment: 12 pages, 5 figures, Latex, Int. J. Mod. Phys.

Achieving geodetic motion for LISA test masses: ground testing result

The low-frequency resolution of space-based gravitational wave observatories such as LISA (Laser Interferometry Space Antenna) hinges on the orbital purity of a free-falling reference test mass inside a satellite shield. We present here a torsion pendulum study of the forces that will disturb an orbiting test mass inside a LISA capacitive position sensor. The pendulum, with a measured torque noise floor below 10 fNm/sqrt{Hz} from 0.6 to 10 mHz, has allowed placement of an upper limit on sensor force noise contributions, measurement of the sensor electrostatic stiffness at the 5% level, and detection and compensation of stray DC electrostatic biases at the mV level.Comment: 4 pages (revtex4) with 4 figure